Forging die



Sept. 4, 1945. D. w. SHERMAN 2,384,349

' FORGING DIE Filed Jan. 27, 1944 Donald W Sherman INVENTOR.

BY V ATTORNE 1.

,2,:s4,:'49 QRGIN DI some wlsnen'nm, Shorew'ootLWlaJsslgniuto O. SmithCorporation, Milwaukee,

corporation of New York P v Application January 27, 1944, Serial No.519,930 I H Clalms.. (cue-so This invention relates to forging dies.

The principal object of the invention is .to provide a forging die forhigh temperature forging and in which a lubricant is secured to theworking face of the die.

According to the invention, the working surface of the die or of a thinliner therefor has a coating of ceramic enamel or the like bondedthereto to serve as a lubricant.

The invention has been applied to the forging of thin sections in oneforging operation as set forth in applicant's copending application,Serial No. 519,940, filed on even' date herewith for Method of forgingand lubricant therefor.

An embodiment of the invention is illustrated in the accompanyingdrawing in which:

Figure 1 is a plan view of the face of a forging Pig. 2 is an enlargedtransverse section of the die taken on line 22 of Fig. 1, together withits mate;

Fig. 3 is an enlarged fragmentary section similar to Fig. 2; and

Fig. 4 is a similar transverse section showing a modified constructionof die without employing a replaceable lining.

The dies illustrated in the drawing were constructed for the forging ofa specially shaped steel plate having thin sections of considerablesurface area. The plate is forged from a round bar about three inches indiameter and several feet long in a single operation of the forgingpress. In order to accomplish this, and in accordance with the methodset forth in the copending application above specified, the bar isheated to swim; close to the melting point of the steel and a ceramicenamel lubricant is employed to line the dies.

The present invention is directed to the construction of the dies andthe application of the ceramic enamel lubricant thereto to obtain themost satisfactory forging results.

The lower die I constitutes a block of metal 2 having a face 0 generallyshaped according to the article being forged and provided with arelatively thin replaceable lining of sheet metal 4, and the latter hasbonded to its working face a continuous uniform coating of ceramicenamel l.

The lining 4 may be formed directly against the face I of the block 2sons to fit tightly and uniformly thereagainst.

The enamel I is applied to the working facethen firing the w re about 100 e. The ming operation fuses the enameling. material and bonds thesame to the steel lining 4 throughout. The upper die I is of similarconstruction with a lining I and ceramic enamel coating 0. The face ofthe upper die I, however, is usually of different shape than that of thelower die i, depending upon the shape of the piece to be formed. Incarrying out the forging operation, the bar 9 to be forged is firstheated thoroughly to above 2400 F. and then subjected to the forgingpressure of the two opposed dies l and '6. In the forging operation thebar I is first engaged by the dies along the center line of the latter,and as the metal of the bar flows laterally under the pressure of thedies thereon, it progressively engages more and more of the die facesuntil it substantially fills the die cavity and takes on the shape ofthe finished forged article.

The ceramic enamel I and I bonded to the working faces of the liningbecomes plastic from the heat of the forging blank 0 and serves as alubricant for the dies. It was found in tests that without the enamel ittook about 1,800 tons pressure to form the forged product described:whereas with the enamel lubricant it took less than 200 tons ofpressure. The softening of the enamel occurs progressively as the metalbeing forged gradually flows laterally in the dies, and therefore afresh supply of lubricant is always being sup plied at the point of fiowof the metal. The bonding of the enamel to the working surface of thedie prevents its being scraped off or pushed ahead of the flowing metal.

The enamel coating should be at least ten thousandths of an inch thickand preferably comprises two or more coatings, one applied on another.The first coat should be of a composition giving good bondingcharacteristics. The enamel is preferably of the hard or glass typefiring at above 1600 F. as distinguished from softer types firing as lowas 1300" 13. However, this may depend upon the shape and composition ofthe article being forged and the forging temperature employed. Asexplained in the copending application referred to, the spread betweenthe firing temperature of the enamel and the temperature to which thework blank is heated for forging should be such as to effect a heatingof the hard enamel to a plastic state to provide its lubricant effect.If the enamel remains too hard, it may obi ectlonably affect the surfaceof the forging. 0n the other hand, if the enamel melts to a liquid statetoo soon it may be scraped off and thereby fail to lubricate. In themodified embodiment of the invention illustrated in Fig. 4, the enamelII is bonded direetlytotheworkingfaeesofthedles II and II which aredimensioned to shape the article without a liner. In employing thisembodiment, the working face of the die is cleaned between each one ortwo forging operations and then reenameled. In the preferred embodimentof Figs. 1, 2 and 3, however, the liner is sufllciently cheap to permitit to be discarded and a new enameled linerplacedinthedieassoonastheenamelhasbecome sumciently destroyed to preventits use. It is usually best to use the enamel only once and to replacethe liner between each forging operation. It is also possible to cleanand reenamel the liners for repeated use.

Various embodiments of the invention may be employed within the scope ofthe accompanying claims.

The invention is claimed as follows:

1. A die for forging operations comprising a die go member having aworking face for shaping an article, and a coating thereon of ceramicenamel bonded thereto.

2.Adieformetalforgingcpuationscomvrhingadiememberhavingaworkingfaceforampingaheatedmetalarticleandahsrdrefractonlubricantwhichsottmsundertheheatofthefilorgingoperationliningtheworkingfaceofflie 3.Adieformetalforgingopmtionscomprbingadieblochasheetmetallinerforthersceoithedieblockandprovidingaworkingfaceforthedie,andaceramieenamelcoatingcoveringsugidworkingfaceandbmidcdtosaldsheetmetal 4.Inadieforhightemperaturemetalforgingoperations,areplsceablemetallininghavingits working surface coated witha vitreous material flredandbondedthereto.

5. In a die for high temperature metal forsinc operations, a glassenamel lubricant coating and bondedto the working surface of the die.

DONALD W. SHERMAN.

